{"data":{"id":"us/40-cfr-52.1971","jurisdiction":"us","citation":"40 CFR 52.1971","heading":"Classification of regions.","body":"The Oregon plan was evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone\nPortland Interstate I IA III I I\nSouthwest Oregon Intrastate II III III III III\nNorthwest Oregon Intrastate III III III III III\nCentral Oregon Intrastate II III III III III\nEastern Oregon Intrastate II III III III III","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS","Subpart MM—Oregon"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"05c33e7b9de6d6b764ba5bd844aa6ed6b3cbf22959a6d372457b1f2ecdc0e03c","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.1970","next":"us/40-cfr-52.1972"},"notice":"GroundRules: Original legal text. Not legal advice."}